Effects of Vitamin C on Tooth Growth in Guinea Pigs

Author

Devneet Mohanty

Background

A classic biological experiment was conducted to determine the effects of vitamin C on the tooth length of guinea pigs. The data records the length of odontoblasts (cells responsible for tooth growth) under different supplement types and dosages in 60 guinea pigs. In this brief analysis, I will:

Compute summary statistics for tooth length, categorized by supplement type and dose level.
Visualize the impact of vitamin C dosage and delivery method on guinea pig tooth growth using an interactive boxplot.
Interpret whether the form of supplementation (OJ vs. VC) and dosage amount significantly influence tooth development.

Summary Statistics

We begin by calculating the mean and standard deviation of tooth length, grouped by supplement type and dosage level, using the dplyr package.

Summary Statistics of Tooth Length by Supplement and Dose
Supplement	Dose_mg	Mean_Tooth_Length	SD_Tooth_Length
OJ	0.5	13.23	4.46
OJ	1.0	22.70	3.91
OJ	2.0	26.06	2.66
VC	0.5	7.98	2.75
VC	1.0	16.77	2.52
VC	2.0	26.14	4.80

Effect of Supplement and Dose on Tooth Length

The following interactive boxplot compares Tooth Length (len) across different dosage levels and supplement types. It helps us observe how increasing the vitamin C dose affects tooth growth and whether the delivery method (Orange Juice vs. Vitamin C supplement) plays a role.

This visualization allows us to:

Observe how increasing doses of Vitamin C (0.5, 1.0, and 2.0 mg) influence the average tooth growth in guinea pigs.
Examine whether the form of Vitamin C delivery — either as Orange Juice (OJ) or a pure supplement (VC) — has a differential effect on tooth development.
Identify potential interaction effects between dosage and supplement type, especially if the growth trends differ significantly across groups.
By comparing the spread and central tendency (median) of tooth length distributions within each group, we aim to determine the optimal dose and delivery method for promoting tooth growth.

Interpretation of Relationship

There’s a clear positive effect of increasing vitamin C dosage on tooth length: higher doses generally result in longer teeth.
At each dose level, orange juice (OJ) tends to produce slightly greater tooth growth than the synthetic vitamin C supplement (VC), especially at the 0.5 mg and 1.0 mg levels.
These patterns suggest that both dosage and delivery method significantly influence tooth development in guinea pigs, with a potential interaction between the two factors.

--- title: "Effects of Vitamin C on Tooth Growth in Guinea Pigs" author: "Devneet Mohanty" format: html: code-fold: true code-tools: true code-line-numbers: true fontsize: 1.2em toc: true toc-title: '**Contents**' embed-resources: true grid: body-width: 800px theme: - superhero - custom-theme.css css: custom-theme.css revealjs: slide-number: true incremental: false auto-stretch: false embed-resources: true center: true theme: - custom-theme.css urlcolor: blue progress: true controls: true execute: eval: true echo: false warning: false --- ## Background A classic biological experiment was conducted to determine the effects of **vitamin C** on the tooth length of guinea pigs. The data records the **length of odontoblasts (cells responsible for tooth growth)** under different supplement types and dosages in 60 guinea pigs. In this brief analysis, I will: 1. Compute summary statistics for **tooth length**, categorized by **supplement type** and **dose level**. 2. Visualize the impact of **vitamin C dosage** and **delivery method** on guinea pig tooth growth using an interactive boxplot. 3. Interpret whether the **form of supplementation** (OJ vs. VC) and **dosage amount** significantly influence tooth development. --- ## Summary Statistics We begin by calculating the mean and standard deviation of **tooth length**, grouped by **supplement type** and **dosage level**, using the `dplyr` package. ```{r} #| label: desc-stat-tooth #| echo: false #| message: false #| warning: false library(dplyr) library(knitr) library(kableExtra) # Calculate summary statistics stats_tooth <- ToothGrowth %>% group_by(Supplement = supp, Dose_mg = dose) %>% summarise( Mean_Tooth_Length = round(mean(len), 2), SD_Tooth_Length = round(sd(len), 2), .groups = "drop" ) # Display as styled HTML table stats_tooth %>% kable("html", caption = "Summary Statistics of Tooth Length by Supplement and Dose") %>% kable_styling( bootstrap_options = c("striped", "hover", "condensed", "responsive"), full_width = FALSE, position = "center" ) ``` ## Effect of Supplement and Dose on Tooth Length The following interactive boxplot compares [Tooth Length (len)]{style="color: darkgreen;"} across different dosage levels and supplement types. It helps us observe how increasing the vitamin C dose affects tooth growth and whether the delivery method (Orange Juice vs. Vitamin C supplement) plays a role. This visualization allows us to: - Observe how increasing doses of Vitamin C (0.5, 1.0, and 2.0 mg) influence the average tooth growth in guinea pigs. - Examine whether the form of Vitamin C delivery — either as Orange Juice (OJ) or a pure supplement (VC) — has a differential effect on tooth development. - Identify potential interaction effects between dosage and supplement type, especially if the growth trends differ significantly across groups. - By comparing the spread and central tendency (median) of tooth length distributions within each group, we aim to determine the optimal dose and delivery method for promoting tooth growth. ```{r} #| label: toothgrowth-boxplot #| echo: false #| message: false #| warning: false library(ggplot2) library(plotly) # Convert dose to factor for plotting ToothGrowth$dose <- as.factor(ToothGrowth$dose) # Create boxplot p_box <- ggplot(ToothGrowth, aes(x = dose, y = len, fill = supp)) + geom_boxplot(alpha = 0.7, outlier.color = "red", outlier.size = 2) + labs( title = "Tooth Length by Dose and Supplement Type", x = "Supplement Type Dose (mg)", y = "Tooth Length (mm)", fill = "Supplement Type" ) + theme_minimal(base_size = 14) ggplotly(p_box) ``` ## Interpretation of Relationship - There’s a clear positive effect of increasing vitamin C dosage on tooth length: higher doses generally result in longer teeth. - At each dose level, orange juice (OJ) tends to produce slightly greater tooth growth than the synthetic vitamin C supplement (VC), especially at the 0.5 mg and 1.0 mg levels. - These patterns suggest that both dosage and delivery method significantly influence tooth development in guinea pigs, with a potential interaction between the two factors.